Apparatus for rapid fluid compacting



Dec. 1, 1970 c. a. BOYER APPARATUS FOR RAPID FLUID COMPACTING 2Sheets-Sheet 2 Filed Dec. 12, 1968 //V VEN TOR. CHARL 58 B. BOYER A rlorney 3,543,345 APPARATUS FOR RAPID FLUID COMPACTING Charles BenjaminBoyer, Columbus, Ohio, assiguor to Crucible Inc., Pittsburgh, Pa., acorporation of Delaware Filed Dec. 12, 1968, Ser. No. 783,237 Int. Cl.B29g 1/00 US. Cl. 18-16 7 Claims ABSTRACT OF THE DISCLOSURE In the artof powder metallurgy, wherein metal in powdered form is heated to anelevated temperature and while at said temperature subjected to pressureto form a dense metal compact, it is well known to perform thisoperation in a fluid-pressure vessel, commonly termed an autoclave. Bythe use of an autoclave, as opposed to mechanical compacting, moreuniform pressure application is achieved. With many powder-metallurgyproducts, such as tool-steel articles, the quality of the product isgreatly improved by this uniform pressure application.

Prior to the present invention, however, the use of an autoclave for thecompaction of metal articles, and particularly tool-steel articles, hasnot been commecrcially feasible. This resulted from the fact that manymetal articles, and particularly tool steels, must be compacted atextremely high temperatures. For tool steels, the compacting temperaturemay be typically within the range of 1800 to 2200 F. To achieve thesecompacting temperatures, the powdered metal charge, prior to compacting,must be heated for times on the order of five hours or longer.Obviously, if the charge is heated within the autoclave to compactingtemperature, which may take about five hours, only a very few compactscould be produced by a single autoclave. Consequently, an operation suchas this is not suitable for commercial production from the economicstandpoint. Alternately, the powdered-metal charge may be heated tocompacting temperature within a furnace, and when compacting temperaturehas been achieved the charge may be then transferred to the autoclavefor compacting. By the use of a plurality of furnaces to service asingle autoclave, the production rate for each autoclave may besubstantially increased over the practice of heating the charge tocompacting temperature within the autoclave. This practice, however,also has not been feasible from the commercial standpoint. This resultedfrom the fact that by the time the powdered metal charge is transferredfrom the furnace and placed in the autoclave, the autoclave is sealed,and then pressurized to the required compacting pressure, the powderedmetal charge has cooled to a temperature less than that required forsatisfactory compacting. This sequence, which prior to the presentinvention has been necessary for autoclave compacting, may take an houror more for completion. In view of this, it may be readily seen that thehigh compacting temperatures on the order of 1800 to 2200 R, which arerequired in the compacting of tool-steel compositions, cannot bemaintained throughout the loading, sealing and pressurizing sequence.

nitecl States Patent 6 It is, accordingly, the primary object of thepresent invention to provide an apparatus for rapidly compactingpowedered metals.

Another, more specific, object of the invention is to provide anapparatus for rapidly compacting powderedmetal charges by providing forquick (typically one minute or less) pressurization of the autoclave forcompacting.

Another more specific object of the invention is to provide for rapidcompacting in an autoclave by providing fast-acting apparatus forclosing and sealing the autoclave upon loading of the powdered-metalcharge therein.

Yet another object of the invention is to provide an apparatuspermitting rapid fluid-pressure compacting of powdered-metal charges inan autoclave by the combination of an arrangement for quickly closingand sealing the autoclave with an arrangement for quickly pressurizingthe autoclave after a powdered-metal charge has been loaded and theautoclave has been scaled.

These and other objects of the invention, as well as a completeunderstanding thereof, may be obtained from the following descriptionand drawings, in which:

FIG. 1 is an assembly view of one embodiment of apparatus in accordancewith the present invention in elevation and partial section;

FIG. 2 is a side view in elevation of the apparatus of FIG. 1 with theplug closure in sealing position;

FIG. 3 is a detailed view of the plug closure used with the apparatus ofFIGS. 1 and 2; and

FIG. 4 is a side view of the plug closure of FIG. 3.

In its broaded aspects, the apparatus of the invention embodies apressure vessel, or autoclave, that is adapted to receive apowdered-metal charge that has been heated to an elevated temperature,on the order of for example 1800 to 2200 F., and is contained within ametal container for compacting. A plug is provided as a top closure forthe pressure vessel. The plug is housed at a position above and offsetfrom the open top of the autoclave. Means are provided for quicklymoving the plug from this offset position to a position in axialalignment with the autoclave after a charge of powdered metal has beenplaced therein for com-pacting. When the plug is in axial alignment withthe autoclave top, means are provided for quickly moving it axially intoclosed, sealing engagement with the autoclave. By this arrangement, theautoclave may be quickly sealed against the atmosphere immediately uponloading of a powdered-metal charge for compacting. Upon scaling in themanner above described, the autoclave is quickly pressurized (typicallyone minute or less) by the introduction of high-pressure fluid thereto,which immediately compacts the powderedmetal charge therein to a densitytypically of percent or more. In accordance with the present invention,quick pressurization is achieved by having an auxiliary or storagepressure vessel. Prior to loading the autoclave, the storage vessel ispumped to a high fluid pressure. Highvolume valving means are providedbetween the storage vessel and the autoclave. Immediately upon sealingof the autoclave, with the powdered-metal charge to be compactedtherein, the valving means are operated to quickly transfer thehigh-pressure fluid from the storage vessel to the autoclave. By thisarrangement, the conventional pumping of the autoclave to achieve therequired high fluid pressure and the long times required for thispumping operation are eliminated. Therefore, the autoclavepressurizingoperation, which typically may take an hour or more if pumping is used,may now be achieved within one minute or less.

With reference to the drawings, and for the present to FIGS. 1 and 2thereof, there is shown an autoclave assembly, designated generally withthe numeral 10. The autoclave assembly has an elongated cylindricalpressure vessel 12 with a fixed lower closure 14 supporting a basepedestal 16 upon which a container (not shown) filled with powderedmetal to be compacted is supported. The top of the pressure vessel 12has an opening 18. The

interior of the pressure vessel is provided with a liner member 20,which is preferably constructed from a temperature-resistant steel. Theliner 20 is preferably readily removable. In this manner, the insidediameter of the pressure vessel may be varied in accordance with thesize of the charge being compacted. This serves to minimize heat lossfrom the charge. Near the top of the pressure vessel 12 there are twoaxially aligned horizontal drillings '21, which extend through thepressure vessel walls. Above the drillings and adjacent the top surfaceof the pressure vessel are two parallel rods 22. Connected to the rods22 are sliders 24 that slidably or movably support a housing 26 on therods 22. Within the housing 26 there is suspended, as best shown inFIGS. 3 and 4, a plug 27. The plug is connected at its top surface at 28to a ram 30 that is connected for actuation to a conventional hydraulicpiston-cylinder arrangement 31. The housing 26, with the plug 27suspended therein, is moved to a position atop the pressure vessel 12 bythe action of ram 32 as part of a hydraulic piston-cylinder arrangement34. When it is desired to close the autoclave, which is after a chargehas been placed therein for compacting, the piston-cylinder arrangement34 is actuated to extend ram 32 and thus move the housing horizontally,or to the left, as viewed in FIG. 1, to a position where the plug 27 isaxially aligned with the top opening 18 in the pressure vessel, At thistime, ram 30 is actuated by its associated hydraulic pistoncylinderarrangement to push the plug 27 axially into sealing engagement withinthe pressure vessel. The lower portion of the plug 27 is provided withan annular notch 36 to which is attached a sealing ring 38. When theplug 27 is inserted into the pressure vessel for closure thereof, thesealing ring 38 seats and seals against the top surface 40 of thepressure vessel liner 20. With the plug so positioned, the openings 20in the pressure vessel walls are aligned with a similar diameterhorizontal drilling 42 through the plug 27. A pin 44 is supported onrollers 46 in axial alignment with openings 21 in the pressure vesseland 42 in the plug. The diameter of the pin 44 is substantially the sameas that of openings 21 and 42. The end of the pin 44 opposite that ofthe pressure vessel is connected as at 48 to a ram 50 of piston-cylinderarrangement 52. With the plug in the closed position within the pressurevessel, the piston-cylinder arrangement 52 is actuated to extend the ram50, and in this manner move the pin 44 through the openings 21 in theautoclave wall and the drilling 42 through the plug. In this manner, theplug 27 is locked in sealing engagement in the closed position in thepressure vessel.

With the plug 27 in the closed position in the pressure vessel, asdescribed above, the pressure vessel is then pressurized to compact thepowdered-metal charge therein. The apparatus for this purpose includesan auxiliary or storage vessel 54 connected to a fluid pump 56, which isadapted to fill said vessel 54 with high-pressure fluid, such as heliumgas. The vessel 54 is connected to the pressure vessel via high-pressurelines 58 having highpressure valves 60, and to a vent valve 59 viahighpressure line 61. The lines 58 extend into the pressure vessel viadrillings 62 in the pressure vessel lower fixed closure 14. The ventvalve 59 and the valves 60 are closed during pressuring of the storagevessel 54. This operation is completed prior to the loading of thepressure vessel 20 with the powdered-metal charge to be compacted. Uponloading and sealing of the pressure vessel, the valves 60 are opened andhigh-pressure fluid from the storage vessel 54 is immediatelytransferred to the pressure vessel, which causes the powdered-metalcharge therein to be compacted. The valves are then closed. Aftercompacting, vent valve 59 is opened to exhaust the autoclave, the pin 44is withdrawn, the plug 27 is lifted upwardly and out of the pressurevessel and into the housing 26. The housing 26 is then moved along therods 22 to its position offset from the pressure vessel top, which isthe position shown in FIG. 1. The compact may now be removed from thepressure vessel and the vessel is ready to receive another charge forcompacting. A typical overhead crane may be used to load and unloadworkpieces with respect to the pressure vessel.

It is to be understood that in typical commercial opera tion amultiplicity of furnaces will be located adjacent the pressure vessel.The furnaces will be used to simultaneously heat a number ofpowdered-metal charges to compacting temperature, and in this manner asone charge is removed from the pressure vessel a second charge, whichhas been previously heated to compacting temperature, may be immediatelyremoved from a furnace and placed in the pressure vessel for compacting.By using the proper number of furnaces, the pressure vessel may ifdesired be operated on a substantially continuous basis. For thispurpose, a plurality of auxiliary or storage pressure tanks may beemployed so that repressurizing of the autoclave for compacting need notawait the pumping-up of a single storage vessel.

A particularly significant feature of the apparatus of the presentinvention is the utilization of means for quickly pressurizing thevessel or autoclave upon loading. Prior, known fluid-pressure compactingdevices require times of from one-half hour to several hours to acquirethe needed pressures to compact powdered metals, such as tool steelpowders. These excessive times render fluidpressure compactinginapplicable to modern production techniques due to the inefficiency oftime consumption per autoclave load. By utilizing a valve betweenstorage vessel 54 and pressure vessel 12 (or a multiplicity of suchvalves in conduits communicating with a multiplicity of such storagevessels 54 and a pressure vessel 12), it is possible to raise thepressure within autoclave 12 by evening out the pressure between one ormore such storage vessels and the pressure vessel or autoclave in 10minutes or less. This rapid time period renders the apparatus andprocess practical from a production standpoint.

For the purposes of the present specification and the claims, the termquickly pressurized as it applies to the release of pressure from one ormore storage vessels (such as vessel 54) to a pressure vessel (such asautoclave 12) shall mean a time period of 10 minutes or less or it shallmean apparatus capable of effecting such a release of pressure withinsuch a time period.

A valve known as P/N 4010-3119 (50,000 p.s.i. yoke valve air to closeassembly, replaceable seat) manufactured by Autoclave Engineers, Inc. ofErie, Pa. may be used as the valve 60. However, other commerciallyavailable valves capable of effecting the required rapid pressurerelease (10 minutes or less) may also be utilized in the apparatus ofthe present invention.

Although specific embodiments of the invention have been shown anddescribed herein, it is obvious that other adaptations and modificationsmay be made by those skilled in the art without departing from the scopeand spirit of the appended claims.

I claim:

1. Apparatus for producing compacted articles from fully preheatedpowdered "metal charges comprising a first pressure vessel, afluid-tight closure for said vessel, said closure being selectivelypositionable between an open and closed fluid-tight position, a secondpressure vessel, a fluid pump connected to pressurize said secondpressure vessel by introduction thereto of fluid under pressure, andvalving means interposed between said first vessel and said secondvessel for permitting fluid flow from said second vessel, uponpressurization thereof, to

said first vessel, whereby said first vessel may be quickly pressurized.

2. The apparatus of claim 1 wherein said fluid-tight closure isselectively positionable between an open and closed fluid-tight positionby means for moving said closure along a substantially horizontal planeto a position above and in axial alignment with a top opening in saidfirst pressure vessel, means for moving said closure axially to a closedposition within said first vessel opening, and means for securing saidclosure in the closed fluid-tight position, whereby pressurization ofsaid vessel is permitted.

3. The apparatus of claim 2 wherein said fluid-tight closure comprises aplug providing pressure-tight engagement with an interior surface ofsaid first pressure vessel when in said closed position.

4. The apparatus of claim 2 wherein said means for moving said closureincludes a housing, means for supporting said closure Within saidhousing in a vertical position, a horizontal way extending over said topopening in said first pressure vessel, means slidably connecting saidhousing to said way, and means for sliding said housing along said wayto a position wherein said closure is in axial alignment with said topopening.

5. The apparatus of claim 2 wherein said means for securing said closurein the closed fluid-tight position is a pin that extends substantiallyhorizontally through mating passages in said closure and vessel.

6. The apparatus of claim 5 wherein said pin rests on a plurality ofrollers movably supporting said pin during movement through said matingvessel and closure passages.

7. The apparatus of claim 1 having a vent valve for exhausting saidfirst pressure vessel upon the completion of compacting.

References Cited UNITED STATES PATENTS 3,172,153 3/1965 Loomis et a1.18-16 X 3,478,920 11/1969 Pecheck 18-16 X 20 WILLIAM S. LAWSON, PrimaryExaminer

